Comparative activity of the new fluoroquinolone rufloxacin (MF 934) against clinical isolates of gram-negative and gram-positive bacteria.

The antibacterial activity of the new fluoroquinolone rufloxacin (MF 934) was evaluated against 1095 clinical isolates and compared with that of other quinolones and various commonly used antibiotics. Rufloxacin was highly effective against members of the Enterobacteriaceae, inhibiting 98% of the isolates at a concentration of 1 mg/l. Ninety-two percent of Aeromonas hydrophila and 65% Acinetobacter strains tested were inhibited by 1 mg/l of rufloxacin, whereas 98% of methicillin-susceptible and 87% of methicillin-resistant Staphylococcus aureus strains and 76% of coagulase-negative staphylococci strains required 4 mg/l for growth inhibition. The MIC values of rufloxacin for most bacteria were 4-16 times higher than those of ciprofloxacin and norfloxacin. Rufloxacin had little activity against xanthomonads, pseudomonads and enterococci. Approximately 95-96% of isolates of Pseudomonas aeruginosa were inhibited by 2 mg/l of ciprofloxacin and norfloxacin as compared to 29% inhibited by rufloxacin at this concentration.